Pesticide and Environmental Update
Waste Management: It’s
About Thyme
By Laura McGinnis December 16, 2005
A 1,000-head cattle feedlot produces about 146 to 175 tons of wet
manure every week—a problematic figure for feedlot operators and their
neighbors. Despite its benefits as a natural fertilizer, manure is a
source of pathogens and odor. Fortunately, Agricultural Research Service (ARS)
scientists are developing a method to reduce manure’s negative
properties. All they need is a little thyme.
Thymol is the active component in thyme oil, which can be extracted
from a variety of plants, such as thyme and oregano. Because of its
pleasant odor and natural antiseptic properties, thymol appears in a
variety of products, including mouthwash and throat lozenges. ARS
microbiologists Elaine Berry, Vince Varel and Jim Wells discovered that
its qualities can also benefit feedlots. When applied to cattle feedlot
soil in slow-release granules, thymol reduced concentrations of
odor-causing volatile fatty acids (VFAs) and pathogens like coliform
bacteria and Escherichia coli. Berry, Varel and Wells work in the ARS
Nutrition Research Unit, part of the agency’s Roman L. Hruska U.S. Meat
Animal Research Center in Clay Center, Neb.
The researchers observed even more prolonged effects in swine
facilities, which might be due to the pits some swine operators employ to
collect and store manure. The enclosed systems could retain more thymol
than the cattle feedlots, increasing its effectiveness.
The scientists also tested less expensive compounds in the lab,
including terpineol, linalool, plinol and geraniol. Most promoted
reduction of VFAs and pathogens like E. coli and Salmonella. Linalool was
nearly as effective as thymol in the lab, but when subjected to field
studies in the feedlot, thymol outperformed it. This may have been due to
dry weather conditions during the test period, the researchers speculate.
They plan to conduct more tests in the spring, when feedlot conditions
will more closely resemble the slurries in which the compounds were
initially tested.
|
